Manifold for free-piston units



Aug. 16, 1949. w. A, LEDwITH 2,479,045

MANIFOLD Fon FREE-PIsToN UNITS Filed April 15, 1944 .www

ATTORNEY Patented Aug. 16, 1949 MANIFOLD Fon mEE-rrs'ron ums Walter A. Ledwith, Hartford, Conn., assigner te United Aircraft Corporation, v East Hartford, Conn., a corporation of Delaware Application April 15, 1944, Serial No. 531,8

(ci. zzo-w 8 Claims.

This invention relates to a. free-piston unit. particularly to one in which the compressor cylinders have a number of rows of spill ports.

The compressor cylinders of the umts may have intake valves at each end to which gas to be compressed is supplied frequently at a pressure from the ambient atmosphere. A feature of the invention is an intake manifold which extends around the compressor cylinders and in conjunction with end caps provides a connection between all of the intake valves'. y

The copending application of Cooper, Serial No. 531,301, iiled April 15, 1944, on which Patent 2,458,147 was issued on January 4, 1949, described a free-piston unit in which the effective volumes ofthe compressor cylinders are adjusted by successively opening or closing rows of spill ports in the cylinder. A feature of the present invention is a structure which encloses these ports and forms an integral part of the unit. Another feature is the interconnection of the intake valves and the spill ports by the port enclosing structure so that the same pressure may be maintained on the ports and valves.

The rows of spill ports may be successivelyc opened or closed by bands movable on the surface of the cylinder to cover or uncover the ports.' A feature of this invention is the enclosureof the port controlling structure by the structure which encloses the ports and connects the intake valves. Another feature is an intake manifold forming an integral load-carrying part of the unit.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings, which illustrate an em bodiment of the invention.

The single gure is a sectional view through the unit.

The unit shown includes an engine cylinder I0 having reciprocating pistons I2 and I 4 to which 1 compressor pistons I6 and I8 in cylinders 20 and 22 are integrally connected. Sleeves 24 and 28 attached to the compressor pistons complete the reciprocating piston assemblies. The sleeves in combination with stationary'pistons 28 and 30 form air spring cylinders.

The piston assemblies are moved apart by the burning of fuel injected into engine cylinder I0 through one or more nozzles 32. Air compressed in the air spring cylinders on the power stroke returns the piston assemblies. The assemblies are always maintained at equal distances from the center of the engine cylinder by a linkage, not shown.

Intake manifold 42 which extends around the compressor and engine cylinders, conducts air to intake valves 44 in the heads of the compressor cylinders through which air alternately enters opposite ends of the cylinders. The compressed ll, also at opposite ends of the compressor cylinders, and passes into a central scavenge chamber 4l and end chambers 5I and 52. These chambers may be interconnected by a scavenge manifold. not shown.

Compressed gas from the scavenge chambers .enters engine ports M and 5I which are uncovered by pistons I2 and I4 at the end of the power stroke, thereby permitting airto be blown through the engine cylinder. Gas in the engine cylinders is discharged through exhaust ports il into exhaust manifold il.

Each compressor cylinder has a number of axially spaced rows of spill ports 54 which permit discharge of air from the cylinders without comy pression. The rows of ports may be controlled by one or more bands I6 extending around the cylinder and movable axially to close the rows of ports successively. 'I'hese bands and the mechanism bywhich they are moved are a feature of the copending Poole application,A Serial No. 531,308, filed April 15. 1944, on which Patent No. 2,458,198 was issued on January 4, 1949, and will not be described in detail.

The intake manifold 42 has an opening 88 for the admission of air and, as shown, this manifold completely surrounds the compressor cylinders 20 and 22 and the engine cylinder Il. The manifold is spaced from the compressor cylinder to define between the cylinder wall and the manifold a passage by which intake air may reach the n encloses the spill ports 54 together with the port controlling bands 58 so that the pressure at the spill ports is the same-as the compressor intake pressure. The ports provide a connection between the passagel surrounding the compressor cylinder and the interior of the cylinder.

From the foregoing it will be apparent that the intake manifold forms a structural part of the unit and supports the end caps I0 and 12, the latter having passages for intake air and also having the outer scavenge chambers 50 and 52. The actuating means lfor the'bands BB may also be enclosed within the intake manifold, if desired, and the manifold thus forms an enclosure for the spill ports, the port controlling bands and the actuating mechanism. The intake manifold may also form the aligning structure for the entire free-piston y las described in the copending Kalitinsky angl'Ledwith application, Serial No. 531,305, led April 15, 1944, on which Patent No. 2,458,172 was issued on January 4, 1949.

It is to be understood that the invention is not limited to the specific embodiment herein illusair leaves the cylinders through discharge valves 60 trated and described, but may be used in other attractie ways Without departure from its spirit as defined by the following claims.

1 claim:

l. A free-piston unit includingV an engine cylinder and piston, a compressor cylinder and piston, said pistons being connected together for reciprocation as a unit, said compressor cyilnder having a number ofspill ports extending circumi'erentially around and located in the cylindrical wall thereof, means surrounding the compressor cylinder for closing said ports, and a housing extending around and in spaced relation to said compressor cylinder and dening a passage with which said ports connect, said housing enclosing the port closing means and inlet valves in the end of the compressor cylinder remote from the engine cylinder and communicating with said passage.

2. A free-piston unit including an engine cylinder and piston, a compressor cylinder and'piston, said pistons being connected together for reciprocation as a unit, intake valves at opposite ends of the compressor cylinder, said compressor cylinder having a number of spill ports in the cylindrical wall thereof, means surrounding the compressor cylinder for controlling said ports, and a housing surrounding said compressor cylinderin spaced relation thereto forenclosing the ports and the port controlling means and for forming a passage connecting the intake valves.

3. A free-pistn unit including an engine cylinder and piston, a compressor cylinder and piston, said pistons being connected together for reciprocation as a unit, intake valves at least at one end cf the compressor cylinder, said compressor cylinder having a number of spill ports in the cylindrical Wall thereof, means located on the outside of the compressor cylinder for controlling said ports, and a housing surrounding said compressor cylinder in spaced relation thereto and forming an air passage around the compressor cylinder from the intake valves to the spill ports for maintaining the same pressure at the spill ports and the intake valves.

4. A free-piston unit including an engine cylinder and opposed pistons moving therein, compressor cylinders at the ends of the engine cylinder, pistons in said compressor cylinders connected to and moving with said engine pistons, a row of intake valves arranged in a ring at the outer ends of said compressor cylinders, and a substantially cylindrical housing surrounding said compressor and engine cylinders in spaced relation thereto and dening a passage surrounding the compressor cylinders for connecting said intake valves in the opposite compressor cylinders, said housing including end caps forming a part of said passage..

5'. A free-piston unit including an engine cylinder and opposed pistons moving therein, compresser cylinders at the ends of the engine cylinder,l pistons in said compressor cylinders connected to and moving with said engine pistons, a row of intake valves arranged in a ring at the outer ends of said compressor cylinders, spill ports-in the cylindrical lwall of each compressor cylinder, means located on the outside of the compressorcylinder for controlling the ports and a substantially cylindrical surrounding housing for said compressor and engine cylinders in radially spaced -relation to the compressor cylinders, said-housing enclosing said ports and dening a passage around the compressor cylinders for said `4 housing including end caps forming a part of said passage connecting said intake valves with said spill ports.

'6. A free-piston unit including van engine cylinder and opposed pistons moving therein, compressor cylinders at the ends oi the engine cylinder, pistons in said compressor cylinders connected to and moving with said engine pistons, spill ports in the outer cylindrical Wall of each compressor cylinder, means located on the outside of the compressor cylinder for controlling said ports, and a cylindrical housing extending around and in spaced relation to said compressor and engine cylinders-said housing forming an enclosure for the ports and the port controlling means and also forming a manifold communicating with the spill ports on both compressor cylinders.

7. A free-piston unit including an engine cylinder, opposed pistons reciprocating therein, compressor cylinders at the ends of the engine cylinder, pistons in said compressor cylinders connected to and moving with sai'd engine pistons,

a row of intake valves arranged in a ring at each end of each of the compressor cylinders, a substantially cylindrical intake manifold surrounding and in radially spaced relation to the compressor and engine cylinders and forming an annular passage around the compressor cylinders for connecting all of said intake valves, said housing having end caps closing the ends of the housing and forming a part of the passage adjacent to the intake valves at the outer ends of the compressor cylinders.

8. A free-piston 4unit including an engine cylinder, opposed pistons reciprocating therein, compressor cylinders at the ends of the engine cylinder, pistons in said compressor cylinders connected to and moving with said engine pistons, a row of intake valves arranged in a ring at the outer end of each of the compressor cylinders, a substantially cylindrical intake manifold surrounding and in radially spaced relation to the compressor and engine cylinders and forming an annular passage around the compressor cylinders for connecting all of said intake valves, said manifold including end caps at the outer ends of the compressor cylinders.

WALTER A. LEDWITH.

REFERENCES CITED The following references are of record in the ile of this patent:

UNITED STATES PATENTS Number Name Date 877,492 Doelling Jan. 28, 1908 1,468,282 Coulombe Sept. 18, 1923 1,481,358 Dwyer Jan. 22, 1924 1,869,787 Trumble Aug. 2, 1932 1,996,974 Pescara Apr. 9, 1935 2,064,976 Janicke Dec. 22, 1936 2,076,258 Witkiericz Apr. 6, 1937 2,086,163 Junkers July 6, 1937 2,108,890 J anicke Feb. 22', 1938 2,134,920 Kadenacy Nov. 1, 1938 2,189,497 Pescara Feb'. 6, 1940 2,282,562 Cole May 12, 1942 2,319,566 Sunderman et al. May 18, 1943 2,387,603 Neugebauer et al. Oct. 23, 1945 2,414,744 Kalitinsky Jan. 21, 1947 2,426,308 Kalitinskyv Aug. 26, 1947 2,426,309 Kalitinsky Aug. 26, 1947 

